4.1 | Synthesis of PEG-lipid derivatives
End-functionalized PEG-lipids, such as DPPE-PEG-OMe, DPPE-PEG-TAMRA,
DPPE-PEG-biotin, and DPPE-PEG-PyDTP, were synthesized from commercially
available bifunctionalized PEGs and DPPE (Figure 1A and 1B; also see
Supporting Information Figure S1 and S2). Details of the synthesis are
provided in the Supporting Information. All products were identified
using 1H-NMR spectroscopy.